The air quality in Delhi on Thursday slipped into the severe category with the AQI being recorded at 460.
The Dwarka Sector 8 air monitoring centre recorded an air quality index of 496 and Nehru Nagar and JLN Stadium 492.
An AQI between 201 and 300 is considered 'poor', 301-400 'very poor' and 401-500 'severe', while the AQI above 500 falls in the severe plus category.
On Wednesday, the noxious smog resulting from raging farm fires and unfavourable weather had pushed pollution in Delhi-NCR towards the "emergency" zone, prompting authorities to order closure of schools till November 15 -- a second time in two weeks.
The Environment Pollution (Prevention and Control) Authority (EPCA) had also extended the restrictions on dirty-fuel based industries in Delhi-NCR, hot mix plants and stone crushers till the morning of November 15, as the MeT department had said strong winds are expected from Friday, which will bring down the air pollution levels to the very poor category.